Fuel oil spills resulting from storage tank leaks, overfills, or catastrophic floods may pose a sizable risk to human health. Hydrocarbons (and other chemicals spilled during the flood/hurricane) get entrapped along with water inside the pore spaces of solids thus forming so called “ganglia”, a three-dimensional network of pores filled with a mixture of chemicals and water. This problem emerged after a catastrophic flood that occurred in Grand Forks, N. Dak. in April 1997. During the flood, a number of fuel oil tanks in residential basements were ruptured and the spilled hydrocarbons mixed with water and were absorbed into the concrete walls of the basements as well as into wooden flooring and first floor framing wood. Afterward, slow evaporation exposed residents to hydrocarbon vapors, which lasted for years. The residual vapor concentration in some residence basements was high enough that the EPA condemned the houses, resulting in their total destruction.
Porous, solid materials such as concrete, wood, gypsum, brick and like materials can become contaminated with semivolatile organic chemicals which pose a sizeable risk to human health. Semivolatile organic chemicals, such as fuel oil, diesel, and other transportation fuels, come in contact with and can be absorbed into porous, solid materials, typically as a result of spills, leakage, and/or catastrophic floods. Other sources of contaminating semivolatile organic chemicals include household chemicals, solvents, pesticides, herbicides, insecticides, and other industrial chemicals that can be absorbed into porous materials due to commercial, industrial or home use. Semivolatile organic chemicals can also be absorbed into porous materials due to intentional acts of sabotage where these organic chemicals are used as chemical warfare agents or delivered in conjunction with other chemical warfare agents.
Unfortunately, common remediation techniques, such as heating and pump-and-treat technologies, prove to be inefficient for the removal of semi-volatile organic chemicals from concrete and wood. For example, heating causes pollutants to penetrate deeper within concrete blocks, which inhibits remediation and merely delays the release of the organic vapors into the ambient air. Treating surfaces with soap also does not work in this application. Surfactants can not reach the organic chemicals trapped in the ganglia and thus are not effective in causing these chemicals to be removed from the material.
The problem is not limited to hydrocarbons and/or floods. For instance, military munitions production and storage facilities may be heavily contaminated with hazardous explosives and the by-products of their manufacture, such as trinitrotoluene (TNT) and 2, 4-dinitrotoluene (DNT). Common remediation techniques have been shown to be ineffective in these applications as well.
It is evident that there is a compelling need for an efficient method of removing organic chemicals from the pore spaces of monolith-type solids. The present invention demonstrates how an externally applied adsorbent can be used to reduce the amount of semi-volatile organic chemicals absorbed into porous, solid materials upon application of the applied adsorbent to the surface of the building materials.